[WIP] Varnish Vcl generator command

app/code/Magento/PageCache/Api/VclGeneratorInterface.php

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+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\PageCache\Api;
+
+/**
+ * @api
+ */
+interface VclGeneratorInterface
+{
+    /**
+     * Return generated varnish.vcl configuration file
+     *
+     * @param int $version
+     * @return string
+     */
+    public function generateVcl($version);
+}

app/code/Magento/PageCache/Api/VclTemplateLocatorInterface.php

@@ -0,0 +1,26 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\PageCache\Api;
+
+use Magento\PageCache\Exception\UnsupportedVarnishVersion;
+
+/**
+ * Vcl template locator interface
+ *
+ * @api
+ */
+interface VclTemplateLocatorInterface
+{
+    /**
+     * Get Varnish Vcl template
+     *
+     * @param int $version
+     * @return string
+     * @throws UnsupportedVarnishVersion
+     */
+    public function getTemplate($version);
+}

app/code/Magento/PageCache/Console/Command/GenerateVclCommand.php

@@ -0,0 +1,275 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\PageCache\Console\Command;
+
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\Console\Cli;
+use Magento\Framework\Filesystem\DriverPool;
+use Magento\Framework\Filesystem\File\WriteFactory;
+use Magento\Framework\HTTP\PhpEnvironment\Request;
+use Magento\Framework\Serialize\Serializer\Json;
+use Magento\PageCache\Api\VclGeneratorInterfaceFactory;
+use Magento\PageCache\Model\Config;
+use Magento\PageCache\Model\Varnish\VclTemplateLocator;
+use Magento\Store\Model\ScopeInterface;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+
+class GenerateVclCommand extends Command
+{
+    /**
+     * Access list option name
+     */
+    const ACCESS_LIST_OPTION = 'access-list';
+
+    /**
+     * Backend host option name
+     */
+    const BACKEND_HOST_OPTION = 'backend-host';
+
+    /**
+     * Backend port option name
+     */
+    const BACKEND_PORT_OPTION = 'backend-port';
+
+    /**
+     * Varnish version option name
+     */
+    const EXPORT_VERSION_OPTION = 'export-version';
+
+    /**
+     * Grace period option name
+     */
+    const GRACE_PERIOD_OPTION = 'grace-period';
+
+    /**
+     * Output file option name
+     */
+    const OUTPUT_FILE_OPTION = 'output-file';
+
+    /**
+     * @var \Magento\Framework\Filesystem\Directory\WriteFactory
+     */
+    private $writeFactory;
+
+    /**
+     * @var VclGeneratorInterfaceFactory
+     */
+    private $vclGeneratorFactory;
+
+    /**
+     * @var array
+     */
+    private $inputToVclMap = [
+        self::ACCESS_LIST_OPTION => 'accessList',
+        self::BACKEND_PORT_OPTION => 'backendPort',
+        self::BACKEND_HOST_OPTION => 'backendHost',
+        self::GRACE_PERIOD_OPTION => 'gracePeriod',
+    ];
+
+    /**
+     * @var ScopeConfigInterface
+     */
+    private $scopeConfig;
+
+    /**
+     * @var Json
+     */
+    private $serializer;
+
+    /**
+     * @inheritdoc
+     */
+    protected function configure()
+    {
+        $this->setName('varnish:vcl:generate')
+            ->setDescription('Generates Varnish VCL and echos it to the command line')
+            ->setDefinition($this->getOptionList());
+    }
+
+    /**
+     * @param VclGeneratorInterfaceFactory $vclGeneratorFactory
+     * @param WriteFactory $writeFactory
+     * @param ScopeConfigInterface $scopeConfig
+     * @param Json $serializer
+     */
+    public function __construct(
+        VclGeneratorInterfaceFactory $vclGeneratorFactory,
+        WriteFactory $writeFactory,
+        ScopeConfigInterface $scopeConfig,
+        Json $serializer
+    ) {
+        parent::__construct();
+        $this->writeFactory = $writeFactory;
+        $this->vclGeneratorFactory = $vclGeneratorFactory;
+        $this->scopeConfig = $scopeConfig;
+        $this->serializer = $serializer;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $errors = $this->validate($input);
+        if ($errors) {
+            foreach ($errors as $error) {
+                $output->writeln('<error>'.$error.'</error>');
+
+                return Cli::RETURN_FAILURE;
+            }
+        }
+
+        try {
+            $outputFile = $input->getOption(self::OUTPUT_FILE_OPTION);
+            $varnishVersion = $input->getOption(self::EXPORT_VERSION_OPTION);
+            $vclParameters = array_merge($this->inputToVclParameters($input), [
+                'sslOffloadedHeader' => $this->getSslOffloadedHeader(),
+                'designExceptions' => $this->getDesignExceptions(),
+            ]);
+            $vclGenerator = $this->vclGeneratorFactory->create($vclParameters);
+            $vcl = $vclGenerator->generateVcl($varnishVersion);
+
+            if ($outputFile) {
+                $writer = $this->writeFactory->create($outputFile, DriverPool::FILE, 'w+');
+                $writer->write($vcl);
+                $writer->close();
+            } else {
+                $output->writeln($vcl);
+            }
+
+            return Cli::RETURN_SUCCESS;
+        } catch (\Exception $e) {
+            $output->writeln('<error>'.$e->getMessage().'</error>');
+            if ($output->getVerbosity() >= OutputInterface::VERBOSITY_VERBOSE) {
+                $output->writeln($e->getTraceAsString());
+            }
+
+            return Cli::RETURN_FAILURE;
+        }
+    }
+
+    /**
+     * Get list of options for the command
+     *
+     * @return InputOption[]
+     */
+    private function getOptionList()
+    {
+        return [
+            new InputOption(
+                self::ACCESS_LIST_OPTION,
+                null,
+                InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY,
+                'IPs access list that can purge Varnish',
+                ['localhost']
+            ),
+            new InputOption(
+                self::BACKEND_HOST_OPTION,
+                null,
+                InputOption::VALUE_REQUIRED,
+                'Backend host for configuration',
+                'localhost'
+            ),
+            new InputOption(
+                self::BACKEND_PORT_OPTION,
+                null,
+                InputOption::VALUE_REQUIRED,
+                'Backend post for configuration',
+                8080
+            ),
+            new InputOption(
+                self::EXPORT_VERSION_OPTION,
+                null,
+                InputOption::VALUE_REQUIRED,
+                'Varnish configuration version to export',
+                VclTemplateLocator::VARNISH_SUPPORTED_VERSION_4
+            ),
+            new InputOption(
+                self::GRACE_PERIOD_OPTION,
+                null,
+                InputOption::VALUE_REQUIRED,
+                'Grace period in seconds',
+                300
+            ),
+            new InputOption(
+                self::OUTPUT_FILE_OPTION,
+                null,
+                InputOption::VALUE_REQUIRED,
+                'Save output to target file'
+            ),
+        ];
+    }
+
+    /**
+     * @param InputInterface $input
+     * @return array
+     */
+    private function inputToVclParameters(InputInterface $input)
+    {
+        $parameters = [];
+
+        foreach ($this->inputToVclMap as $inputKey => $vclKey) {
+            $parameters[$vclKey] = $input->getOption($inputKey);
+        }
+
+        return $parameters;
+    }
+
+    /**
+     * Input validation
+     *
+     * @param InputInterface $input
+     * @return array
+     */
+    private function validate(InputInterface $input)
+    {
+        $errors = [];
+
+        if ($input->hasOption(self::BACKEND_PORT_OPTION)
+            && ($input->getOption(self::BACKEND_PORT_OPTION) < 0
+                || $input->getOption(self::BACKEND_PORT_OPTION) > 65535)
+        ) {
+            $errors[] = 'Invalid backend port value';
+        }
+
+        if ($input->hasOption(self::GRACE_PERIOD_OPTION)
+            && $input->getOption(self::GRACE_PERIOD_OPTION) < 0
+        ) {
+            $errors[] = 'Grace period can\'t be lower than 0';
+        }
+
+        return $errors;
+    }
+
+    /**
+     * Get ssl Offloaded header
+     *
+     * @return mixed
+     */
+    private function getSslOffloadedHeader()
+    {
+        return $this->scopeConfig->getValue(Request::XML_PATH_OFFLOADER_HEADER);
+    }
+
+    /**
+     * Get design exceptions
+     *
+     * @return array
+     */
+    private function getDesignExceptions()
+    {
+        $expressions = $this->scopeConfig->getValue(
+            Config::XML_VARNISH_PAGECACHE_DESIGN_THEME_REGEX,
+            ScopeInterface::SCOPE_STORE
+        );
+
+        return $expressions ? $this->serializer->unserialize($expressions) : [];
+    }
+}

app/code/Magento/PageCache/Exception/UnsupportedVarnishVersion.php

@@ -0,0 +1,14 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\PageCache\Exception;
+
+use Magento\Framework\Exception\LocalizedException;
+
+class UnsupportedVarnishVersion extends LocalizedException
+{
+
+}